At present, a fuel cell system including a fuel cell for receiving the supply of a reactant gas (a fuel gas and an oxidizing gas) to generate power has been suggested and put to practical use. Such a fuel cell system is provided with a fuel supply passage for feeding, to the fuel cell, the fuel gas supplied from a fuel supply source such as a hydrogen tank.
Furthermore, a fuel cell system including a variable pressure adjustment valve as a pressure adjustment valve provided on the fuel supply passage so as to adjust the pressure of the fuel gas to be supplied to the fuel cell is known, the variable pressure adjustment valve being configured to exert the applied pressure of the oxidizing gas as a pressure source, thereby adjusting the pressure of the fuel gas to be supplied to the fuel cell (e.g., see Japanese Patent Application Laid-Open No. 2005-150090).